Lubricating system for aircraft superchargers



Dec. 14, 1943. H. E. GRANTZ LUBRICATING SYSTEM FOR AIRCRAFT SUPERCHARGERS Filed Jan. 28, 1942 7 Fig.1.

From Engine Inventor: 32 Howard E. Grantz,

b W 6, AMA

y His Attorney.

Patented, Dec. 14, 1943 nunarcsri iiic srsrsu FOR. AIRCRAFT crnncnsacnas v Howard E. Grants, Swampscott, Mass assignor to General Electric Company, a corporation or New York Application January 28, 1942, Serial No. 428,58!

8 Claims. (61. 184-43) The present invention relates to aircraft superchargers and particularly to arrangements for supplying lubricant thereto.

In connection with aircraft having superchargers driven either from the aircraft engine shaft or by exhaust gases from the aircraft engine or engines, it is'customary to lubricate the superchargers with oil taken from a supply tank. This oil supply tank is ordinarily at a level on the aircraft above that of the supercharger and a supply pipe leads from the oil tank down to the supercharger pressure lubricant pump, usually a rotary pump driven from suitable gearing from the supercharger shaft, from which the oil flows to the parts to be lubricated, then to a sump in the supercharger casing. From the sump, the oil is returned -by a scavenger pump to the oil tank. The oil tank may be the same oil tank as that used -to supply the engine or engines of the aircraft or it may be an oil tank for supplying the supercharger only.

The object of my invention is to provide in connection with a lubricating system of the above type an improved arrangement for automatically shutting oif the oil supply from the tank to the pressure pump it either the pipe line leading from the oil tank to the pressure pump or the pipe line leading from th scavenger pump to the supply tank should be ruptured, thus preventing the oil from draining from the tank; also, for automatically shutting off the oil supply line leading from the oil tank to the pressure pump when the supercharger is not running, for example, when the aircraft is on the round, thus preventing the oil from' drainin from the tank out through the supercharger.

My invention has especially great utility in a case where the oil for lubricating a supercharger is taken from the supply tank for an aircraft engine, since in this case drainage of the oil from till; 011 tank might result in failure oi the en- 8 e.

For a consideration of what I believe to be novel and my invention, attention is directed to the following-specification and the claims ap-- pended thereto.

In the drawing, Fig. 1 i a diagrammatic view of a system embodying my invention, and Fig. 2 is a sectional view of a valve which is located in v the pipe line between the oil tank and the pressure pump.

Referring to the craft supercharger, in the present instance a gas driven supercharger comprising ages turbine -2.

. return pipe line.

wheel of the gas turbine is indicated at s and the nozzle box which supplies exhaust ass to the turbine wheel is indicated at b. Exhaust gases from the aircraft engine are supplied to- The com-- the nozzle box through a conduit 6. pressor inlet is indicated at i and the compressor outlet is indicated at 8. From the comprcsaircraft engine or engines, or it may be the oil tank for the supercharger alone. In the present instance, it is shown as being thesoil tank which supplies lubricant to the aircraft engine or engines, M indicating the pip line leading to the engine or engines, and it indicating the In the return pipe line is an oil cooler 88 of suitable construction.

The oil tank is connected to the inlet of the lubricant pressure pump H by a pipe line 11. Theoutlet tor the scavenger pump is connected to the oil tank by a pipe line it which connects totank it through the oil cooler ll andisinpar allel with the oil return pipe i5 from the ensine. The conduits leading drom the pressure lubricating 'pump ii to the bearings of the an.

percharger and from the sump to, the inlet of the scavenger pump it are not ahown in the drawing, this being not needed for an understanding oi my invention. -It will be understood that the pressure lubricant pump pumps oil from tank l3 and discharges it to the bearings of the supercharger; that from the bearings, the oil flows to a sump in the lower portion of the supercharger casing; and that from the sump, it is returned to the oil tank by the scavenger pump. According to my invention, I provide in pipe line H leading from-tank It to the pressure lubricant pump, a valve structure comprising a valve casing 20 having an inlet opening 2i and a discharge opening 22,-.1t being connected into the pipe line by couplings" and II. In valve casilrbetween theinict and outlet openings drawing, i indicates an airis a cylinder 1! which extends to oneside of the valve casing, as indicated at 2!, its end being closed 'by a cylinder head 2!. On. the side of thevalve body opposite cylinder 25. is a second cylinder 28 of smaller diameter than cylinder II.

and a centrifugal compressorS. The turbine cs; In the valve casing isa valve i y 2! in the air.

2,sse,4so

form oi a piston adapted to slide in cylinder 23.

The valve body has a transverse opening." which is counter-bored from its lower end to provide bore 3|. Spring 32 is held in position in the counter-bore 3| by a snap ring 34* and .a retaining washer 33''. Located between valve body 23 and cylinder head 21 is a spring 33- which biases valve body 38 to the right hand end of cylinder 23, the right hand end of the cylinder forming a stop to position the valve body. When in this position, valve body 28 and ball valve 33 close the passage from inlet 2| to outlet 22. Formed integral with valve body 28 is' a piston 33 which slides in cylinder 28. Piston 38 is connected to valve body 28.-by a stem or neck 31. Connected to the end of cylinder 28 is a pipe line 38 which leads to pipe line i8, cylinder 28 being thus connected to the discharge side of scavenger pump I 2 wherebythe end of piston 33 is subjected to the pressure on the discharge side of the scavenger pump. In piston 38 is a small passage 38 which connects opposite sides of the piston and in valve body 28 is a passage 33 which is somewhat larger than passage 38 and connects cylinder 28 to counter-bore 8| in valve body 28.- In cylinder 23' is a groove 4| in which a guide pin 42 carried by valve body 28 runs. This serves to guide movement of the valve body, .hold it in correct position in the cylinder and permit leakage of oil from the cylinder past piston 28.

When the supercharger is running, both pumps II and I2 being in operation, the pressure of the oil and air being discharged by scavenger pump i2through pipe line l8 to the oil tank is supplied through pipe line 88 to piston 36, causing the piston to move to the left hand end oi cylinder 28 whereby valve body 28 is" moved out of line with the opening through the valve so that oil may flow freely through pipe line H to the pressure pump II. In this connection, it is pointed out that the scavenger pump on a supercharger is that in operation, it pumps oil and also considerable air from the sump to the oil'tank. As long as operating condiitons are normal, the valve in pipe line I! will be held open. If. for any reason,

the pressure in pipe line 38 should fail or should remove from the sump such oil as might be at the time there, after which it would then pump only The air pressure, by reason of the openings 38 and 48, would be not suflicient to maintain valve body 28 in open position against the action of spring 33. Opening 38 is made small enough so that during normal operation but a very limited amount or oil will flow through it. However, when air only is present, the air will flow through opening 38 readily, thus preventing the building up or air pressure on the piston. Should pipe somewhat larger than the oil pressure pump so I3 leaking out through the supercharger "pump and casing. 4

If pipe line H or 33 is ruptured, the scavenger pump will'continue to pump oil from the sump through the pipe line to the pointof' ruptureas long as the valve in pipe line H is open. Under this condition, the scavenger pumpdischarge pressure would 'be that required to pump oil through the return line to the point of rupture in the line. Spring 33 is made to have an initial force sumcient to close the valve against such a pressure or against the maximum air'pressure which the scavenger pump is capable oi produc 1118. whichever is the greater. Spring 33 is designed to hold valve 28 in a closed position against the maximum pressure the scavenging pump can create when pumping air only even it bleeder passage 38 or 30 should become clogged.

Ball valve' 38 forms a priming valve which on starting of the supercharger is opened by the suction of the pressure pump so as to initiate flow of oil. If some of the oil drains from return line l8 when the supercharger is shut down, it will have to be replaced before sumcientpressure can be built up to cause the valve in pipe line I! to open when the supercharger is started up again. Priming valve 38 takes care of this condition. When the supercharger is started up, the pressure pump will draw oil past valve 33 for initial lubricating purposes. Valve body 28 will remain in its 'closed position until such fme as the scavenger pump has built up suiiici: -r pressure in discharge pipe line I8 to move valve body 28 to the left to open the valve. Spring 32 is of such strength that when the aircraft is at lower altitudes, i. e., altitudes of the-highest airports, for example, the suction of pressure pump H is sufflcient to open priming valve 33 while at altitudes above this, it will not do so. Hence, it the return line I8 is ruptured and the valve in line I! closes, the pressure pump will not be able to open the ent statutes, I have described the principle of operation 01' my invention, together with the apparatus which I now consider to represent the best embodiment thereof, but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried line l3 or 33 be ruptured, then the pressure on 1 piston 33 is relieved. permitting the valve to close. Also, when the supercharger is shut down. the valve will close, thus preventing oil from tank out by other means.

What I claim as new and desire to secure by Letters Patent 0! the United States is:

1. In a lubricating system for aircraft, the combination of a machine on the aircraft having parts to be lubricated, a lubricant supply tank located at a level above the machine, a pressure lubricant pump, a scavenger pump, a pipe line connecting the lubricant supply tank to the inlet of the pressure lubricant pump, a return pipe line connecting the discharge side of the scavenger pump to the lubricant supply tank, and a safety valve in the first-named pipe line controlled by the pressure in the return pipe line.

2. In a lubricating system for aircraft, the combination of amachine on the aircraft having parts to be lubricated, a lubricant supply tank located at a level above the machine, a pressure said first-named pipe line comprising a movable lubricant pump. a scavenger pump, a pipe line 3. In a lubricating system for aircraft, the

combination of a machineon the aircraft having parts to be lubricated, a lubricant supply tank located at a level above the machine, a pressure lubricant pump, a scavenger pump, a pipe line connecting the lubricant supply tank to the inlet of the pressure lubricant pump,a return pipe line connecting the discharge side or the scavenger pump to the lubricant supply tank, a valve in the first-named pipe line biased to closed position, a movable abutment connected to the valve to which pressure may be applied to effect opening of the valve, and a pipe line connectingthe movable abutment to said return pipe line.

a. In a lubricating system for aircraft, the combination of a. machine on the aircraft having parts to be lubricated, a lubricant supply tank located at a level above the machine, a pressure lubricant pump, a scavenger pump, a pipe line connecting the lubricant supply tank to the inlet or the pressure lubricant pump, a return pipe line connecting the discharge side of the scavenger pump to the lubricant supply tank, a valve in the first-named pipe linehaving a movable valve body, means biasing the movable valve body to closed position, means responsive to the pressure in said return pipe line for holding said valve body in open position, anda priming body, means biasing said movable body to closed position, a movable abutment to which pressure may be applied to hold the movable body in open position, and means connecting said movable abutment to the return pipe line.

6. In a lubricating system for an aircraft, the

combination of a supercharger on the aircraft having parts to be lubricated, a lubricant supply tank located above the level of the supercharger, a pressure lubricant pump and a scavenger pump driven by the supercharger, for circulating lubricant to said parts, a pipe line connectingthe located at a level above the machine, lubricant I 1 supply tank to the inlet of the pressure pump, a return pipe line connecting the discharge side of the scavenger pump to said tank, a valve in said first-named pipe line comprising a movable body, means biasing said movable body to closed position, a movable abutment to which pressure may be, applied to hold the movablebody in open position, means connecting said mcvableabutment to the return pipe line, and a priming valve carried by said movable body.

7. In a lubricating system for aircraft, the combination of a machine on the aircraft having parts to be lubricated, a lubricant supply tank located at a level above the machine, lubricant pump means, a pipe line connectingthe lubricant supply tank to the inlet of the lubricant-pump means, a return pipe line connecting the dis. charge side of the pump means to the lubricant supply tank, and a safety valve in the first named pipe line controlled by the pressure in the return pipe line. I

8. In a. lubricating system for aircraft, the combination of a machine on the aircraft having parts to be lubricated, a lubricant supply tank pump means, a pipe line connecting the lubricant supply tank to the inlet of the lubricant pump means, aretum pipe connecting the discharge side of the lubricant pump means to the lubricant supply tank, a valve in the first-named valve, and a pipe line connecting the movable abutment to said return pipe line.

. HOWARD E. GRAN'IZ'. 

